(BPT) - When days are short and sunshine is scarce, it's only natural to feel a little out of sorts. The sun is the body's chief source of vitamin D, and for many Americans, clouds and cold temperatures can lead to deficiencies. Fortunately, there are other sources that provide this important vitamin - some of which come in a deliciously edible form.

A handful of all-natural foods, such as eggs, can help you get the vitamin D that you might be missing due to a lack of sunshine. In fact, the USDA recently reviewed egg nutrient data and results showed that one large egg contains 41 IU of vitamin D, 64 percent higher than before. If you live in one of the statistically cloudiest cities in the country, like Syracuse, N.Y., Cleveland, Ohio, or Seattle, Wash. - or even in other places where seasonal gloom makes it hard to catch any rays - make sure you are getting enough of this essential vitamin by making a few adjustments to your diet.

"Vitamin D is a nutrient that should not be overlooked," says registered dietitian Neva Cochran. "In addition to working with calcium to help form and maintain strong, healthy bones, vitamin D also prevents the development of osteoporosis in older adults."

As you plan your shopping list, include items that offer a boost of vitamin D. A number of oil-rich fish species, like salmon, tuna and sardines are good sources of vitamin D. In the produce department, seek out mushrooms like Portobellos and shiitakes; in the dairy cases, look for eggs, milk and orange juice.

Once you have stocked up on these ingredients, look for recipes that combine them for an extra boost of vitamin D. Cochran suggests trying a recipe like a Cherry Tomato and Portobello Omelet, which includes two of those key ingredients - eggs and mushrooms.

Get more egg recipes and nutrition information by "liking" the Incredible Edible Egg on Facebook, following @IncredibleEggs on Twitter, or visiting the Pinterest page.

4. When top surface of eggs is thickened and no visible liquid egg remains, place mushroom filling on one side of the omelet; sprinkle with cheese and parsley. Fold omelet in half with turner. With a quick flip of the wrist, turn pan and invert or slide omelet onto plate. Serve immediately.